1. Field of the Invention
This invention relates to secure electronic transactions and, more particularly, to electronic transactions that use a trusted intermediary to provide improved privacy, authentication, and non-repudiation.
2. Discussion of Related Art
To date, businesses have primarily used paper-based systems to deliver documents. Though there is increasing acceptance of electronic mail (e-mail) to deliver electronic messages, it is considered undesirable for certain transactions, particularly the delivery of important documents. Much of the criticism has focused on e-mail's deficiencies with regard to privacy, authentication, and non-repudiation.
Under conventional e-mail, an electronic eavesdropper can monitor the relevant communication medium and determine the contents of the message. Thus, the system lacks privacy. Moreover, there is no assurance that a received e-mail message has not been tampered with while it was in transit or that the message indeed originated from the indicated sender. Furthermore, though conventional e-mail has an ability to provide acknowledgements to a sender that a message has been received, the acknowledgments may be easily circumvented or falsified, and thus message receipt or delivery may be repudiated.
Secure e-mail systems have been proposed but are believed to be unsatisfactory in certain regards. For example, though secure e-mail encrypts the content of a message, the sender's and receiver's identity may be determined with electronic eavesdropping techniques. In many instances, this information in itself is important and needs to be protected.
Micali has disclosed techniques that may be used to form electronic message systems that provide "simultaneous electronic transactions," or SETs. See, e.g., U.S. Pat. Nos. 5,553,145 and 5,666,420. A SET is disclosed as an "electronic transaction that is simultaneous at least in a logically equivalent way, namely, it is guaranteed that certain actions will take place if and only if certain other actions take place." See, e.g., U.S. Pat. No. 5,553,145 at Col. 7, lines 52-55. "Simultaneity is guaranteed, rather than being just highly probable." See, e.g., U.S. Pat. No. 5,553,145 at Col. 8, lines 55-6. Under one arrangement a third party is used to facilitate the exchange of an encrypted message and a receipt, only if needed, i.e., one of the participants does not follow the protocol. U.S. Pat. No. 5,666,420 Under another arrangement, the third party is always visible and used to facilitate the exchange of encrypted messages for receipts. U.S. Pat. No. 5,553,145.
Micali includes only method claims and in this regard it is not clear whether Micali considers the disclosures as enabling to systems or devices. The techniques are disclosed at a generalized level with many variants, but there is essentially no disclosure of the devices, software, or specific algorithms. Thus, there is little or no disclosure on how to implement such a system in a real world context that must address regulatory concerns of encryption. Likewise, there is little or no disclosure of how to integrate the disclosed techniques with existing e-mail systems. These systems represent a large sunk cost both in terms of equipment and user-training.
There is a need in the art for an electronic message system that provides privacy, authentication of participants, and non-repudiation. There is, moreover, a particular need for an electronic message system in which it is difficult to detect that a given sender is sending a message to a given recipient. Preferably, the system should be adaptable to easily address the various regulatory requirements concerning encryption, and preferably, the system should address the myriad of ways in which users receive conventional e-mail.